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blk-stat: make q->stats->lock irqsafe

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blk-iocost calls blk_stat_enable_accounting() while holding an irqsafe lock
which triggers a lockdep splat because q->stats->lock isn't irqsafe. Let's
make it irqsafe.

Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: cd006509b0 ("blk-iocost: account for IO size when testing latencies")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2020-09-01 14:52:32 -04:00 committed by Jens Axboe
parent 5aeac7c4b1
commit e11d80a849
1 changed files with 11 additions and 6 deletions
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17
block/blk-stat.c
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@ -137,6 +137,7 @@ void blk_stat_add_callback(struct request_queue *q,
struct blk_stat_callback *cb)
{
unsigned int bucket;
unsigned long flags;
int cpu;
for_each_possible_cpu(cpu) {
@ -147,20 +148,22 @@ void blk_stat_add_callback(struct request_queue *q,
blk_rq_stat_init(&cpu_stat[bucket]);
}
spin_lock(&q->stats->lock);
spin_lock_irqsave(&q->stats->lock, flags);
list_add_tail_rcu(&cb->list, &q->stats->callbacks);
blk_queue_flag_set(QUEUE_FLAG_STATS, q);
spin_unlock(&q->stats->lock);
spin_unlock_irqrestore(&q->stats->lock, flags);
}
void blk_stat_remove_callback(struct request_queue *q,
struct blk_stat_callback *cb)
{
spin_lock(&q->stats->lock);
unsigned long flags;
spin_lock_irqsave(&q->stats->lock, flags);
list_del_rcu(&cb->list);
if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting)
blk_queue_flag_clear(QUEUE_FLAG_STATS, q);
spin_unlock(&q->stats->lock);
spin_unlock_irqrestore(&q->stats->lock, flags);
del_timer_sync(&cb->timer);
}
@ -183,10 +186,12 @@ void blk_stat_free_callback(struct blk_stat_callback *cb)
void blk_stat_enable_accounting(struct request_queue *q)
{
spin_lock(&q->stats->lock);
unsigned long flags;
spin_lock_irqsave(&q->stats->lock, flags);
q->stats->enable_accounting = true;
blk_queue_flag_set(QUEUE_FLAG_STATS, q);
spin_unlock(&q->stats->lock);
spin_unlock_irqrestore(&q->stats->lock, flags);
}
EXPORT_SYMBOL_GPL(blk_stat_enable_accounting);